Light-emitting diode planar array light source system for defect detection of highly reflective surface

Abstract

For defect detection of objects with highly reflective surfaces, the diffuse light source has reflected light interference, which leads to the blurring of the edge of the defect area. In response to the problem that the problem that diffuse light source is difficult to highlight the surface defects of highly reflective objects, an LED planar array light source system is designed. It is composed of four tilted planar light sources, which can produce highly directional and high-brightness striped structured light on the target surface, thereby improving the gray value gap of the surface defects of highly reflective objects concerning the background. At the same time, to solve the light intensity change caused by the oblique off-axis illumination of the plane light source, the nonlinear constraint is used to optimize the illumination uniformity of the tilted non-focusing direction. Through software simulation and tracking, a stripe-structured light scheme with a period of 12.5 mm and an area of 200 mm×300 mm was designed, and the corresponding planar array light source system was built for defect detection experiments. The experimental results show that the accuracy rates of pits, scratches, and abrasions are 96.8%, 91.6%, and 95.8%, respectively.